1. Field of the Invention
The present invention relates to an electrolytic deposition display apparatus using electroplating for light modulation and a drive method thereof, and more particularly to a display apparatus suitable for the so-called electronic paper and a drive method thereof.
2. Description of the Related Art
In recent years, the development of the electronic paper has been actively performed as a display apparatus having high visibility and little power consumption. An electrolytic deposition display apparatus using electroplating for light modulation has been observed as a display apparatus suitable for such electronic paper from the point of view of light resistance. Examples of such electrolytic deposition display apparatus are described in Japanese Patent Applications Laid-Open No. 2003-337350 and No. 2004-170850.
Japanese Patent Application Laid-Open No. 2003-337350 discloses a display apparatus displaying an image by applying a voltage to each pixel with electrodes arranged in a matrix to precipitate or dissolve electroplating. Then Japanese Patent Application Laid-Open No. 2003-337350 discloses the drive method of selectively applying the voltage of a precipitation critical voltage (threshold voltage) or more to a pixel at which electroplating is precipitated to perform the address drive and of adding a voltage lower than the precipitation critical voltage to the pixel after the address drive. To put it concretely, the method precipitates a crystal, which becomes a nucleus, at a predetermined pixel by the address drive of applying the voltage of the precipitation critical voltage (threshold voltage) or more to the pixel. After that, the method additionally precipitates electroplating at the pixel subjected to the address drive or holds the written state of the pixel by applying a voltage lower than the precipitation critical voltage (threshold voltage).
Moreover, Japanese Patent Application Laid-Open No. 2004-170850 discloses the method of displaying gradations by controlling the time of adding the precipitation critical voltage to the pixel electrodes. Japanese Patent Application Laid-Open No. 2004-170850 discloses the method of controlling the time of adding the precipitation threshold voltage by dividing the time of applying the precipitation threshold voltage into a plurality of sub fields and by selecting the application of the voltage to each sub field. Thereby the method of Japanese Patent Application Laid-Open No. 2004-170850 realizes a multiple gradation display.
However, Japanese Patent Application Laid-Open No. 2003-337350 does not disclose the performance of any multiple gradation displays, although the publication discloses the capability of performing a binary (black-and-white) display. Moreover, it is not easy to realize a multiple gradation display by the method of Japanese Patent Application Laid-Open No. 2003-337350 in consideration of the timing of selecting a pixel in an electrolytic deposition display apparatus arranging a plurality of pixels in a matrix therein.
Moreover, a selected pixel is in the state in which the voltage of the precipitation threshold voltage or more is always applied thereon by the method of Japanese Patent Application Laid-Open No. 2004-170850, and that state influences the surface state of the precipitated electroplating. Consequently, it is difficult to form the electroplating having a good reflection property or a good absorption property, and there is the possibility that it is impossible to obtain a good gradation property.